20.3 cm SK C/34 naval gun

These built-up guns consisted of a rifled tube encased within an inner and outer jacket with a horizontal sliding breech block. The breech was sealed with an 18 kg (40 lb) brass case containing 30 kg (66 lb) of smokeless powder with a 160 gram (5.6 oz) gunpowder igniter. A cloth bag containing an additional 21 kg (40 lb) of smokeless powder and 380 grams (13 oz) of gunpowder was loaded between the projectile and the brass case. Each gun could fire approximately five rounds per minute. Useful life expectancy was 510 effective full charges (EFC) per barrel. ==Naval service==

, , and each mounted eight of these guns in 248-tonne Drh LC/34 twin turrets with a maximum elevation of 37 degrees. ==Coast defence guns==

The four turrets intended for the incomplete cruiser were installed as coastal artillery in France. The turrets A (Anton) and D (Dora) at Battery Karola on the Ile de Re (4./Marine Artillerie Abteilung 282). And the turrets B (Bruno) and C (Cäsar) at Battery Seydlitz on the Ile de Croix (5./Marine Artillerie Abteilung 264). ==Railway guns==

Eight barrels from the incomplete cruiser were given to the army and followed rebuild to 20.3 cm K (E) railway guns. ==Shell trajectory==